Indicating instrument



Oct. 3, 1939.

E. L. VAIL INDICATING INSTRUMENT Original Filed Jan. 14, 1937 n wma o mL,0;

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ATTORNEY.

JPatented Oct. 3, 1939 INDICATING INSTRUMENT Edgar L. Vail, New York, N.Y., assgnor to Jaeger Watch Company, Inc., New York, N. Y., acorporation of New York Original application January 14, 1937, SerialNo.A

120,537.A v Divided and this application April l11, 1938, Serial No. 2

S-Claims.

ground speed. Hence, it is desirable to provide anv instrument whichindicates the true ground speed as well as the air speed. Such a device,however, to be most useful to the pilot, must be so designed that thevarious scales are located in a con-r venient position and are `easilyread and interpreted without the necessity for any mathematicalcalculations.l Furthermore, any adjustment mechanism must be simple andreadily accessible inasmuch as the adjustment must be effected by thepilot-while in flight and at irregular periods in accordance with datareceived from the ground.

It is accordingly an object of the present invention to provide anovelinstrument of the above type which is simple and light inconstruction, convenient to adjust and read and dependable in operation.f

Another object is to provide such a novel instrument which may bereadily set or adjusted to compensate for different wind velocities soas to indicate the .true ground speed.

Another object is to provide a novel instrument of the above type inwhich' both the air speed and ground speed are indicated on con- Variousother objects centrically located scales. will be apparent as the natureof the invention is more fully disclosed.

A feature of the invention consists in the provision, in an instrumentof the above type, of a scale which may be, shifted with respect to apointer by an amount proportional to the wind velocity so that .thecorrected reading represents the true ground speed.

Another feature consists in the provision of two adjacent scaleswhichiegister with the same pointer, one scale being stationary andbeing graduated to indicate theair speed and the other scale beingadjustable' and being` graduated to indicate the ground speed.

Another featureoconsists in the provision of a wind velocity scale andan adjusting knob by which the movable .scale may be easily adjusted tocompensate for various wind velocities.

Various other features consist in the combinations of parts and detailsof construction hereinl after more fully set forth.

In one embodiment of theA invention, the instrument comprises a standardmechanical or electrical tachometer driven by a propeller which ismounted on-the vehicle in the outside medium as, for example, on thestrut of 'the aircraft or, in the case of a Water-borne vessel, ismounted in the surrounding Water, in a position to be driven at a speedproportional to the speed of the craft through the medium. Thetachometer actuates a conventional speedometer mechanism equipped with apointer which is movable over a lscale to indicate the air speed andalso drives an odometer Which integrates the speed to indicate the totaldistance or mileage with respect to the air. In accordance with thepresent invention, a

second scale is mounted concentric with the first ond od/owmeter whichis driven from thefirst odometer through a variable speed gear train,the ratio of which is adjustable in accordance with the' movement of theadjustable scale to. cause the second odometer to compensate for thewind velocity and to indicate the true ground miles flown. l

Although the novel features which are believed to be characteristic ofthis inventionare pointed out more particularly in the claims appended'hereto, the broader aspects4 of the invention will Y be betterunderstood by referring to the following description, taken inconnection with the accompanying drawing, in which oneembodiment of theinvention has been sety forth for purposes yof .illustration only.

1y in section, of an indicating instrument constructed in-accordancewith this invention;

Fig. 2 is a section taken on the line 2--2 of In the' drawing, Fig. 1 isa front elevation, part;

Fig. 1 showing the position of the adjusting knob and associatedmechanism; and, Fig. 3 is a section taken on the line 3-3 'of Fig. 1showing the4 variousdetails of construction.

Referring to the drawing more in detail, the instrument is shown ash'iving a casing III provided with an outer peripheral flange II aand acentral circular plate I2 which is secured thereto by suitable means,such as screws, not' shown. 'I'he plate I2 is provided at its peripherywith a scale graduated to cooperate with a pointer 30 for indicating airspeedin suitable units, such as milesper hour. In the example shown, thescale Il is graduated to read from zero to 300 miles per hour, althoughit is to be understood that various other designations may be employed,depending upon the particular purpose of the instrument.

For indicating the ground speed, there is provided a movable ring Ilwhich is adjustable about the periphery of the plate I2. As shown morein detail in Fig. 3, the ring I5 may be provided with an inner ange I6which seats in a recess I'I formed at the periphery of the plate I2. e

Theplate- I2 is shown as formed by two discs I2a and I2b whichareseparated at their periphery to form the recess I1. It is obvious,however, that other suitable constructions can be used to provide anarrangement such that the ring I5 is supported by and is sli'dablearound the periphery of the plate.

The ring Il is provided with a scale 2li having graduations similar tothe scale I4' and being adapted to cooperate with the pointer 30 forindicating ground sped in the manner to be pointed out. The outer'periphery of the ring I5 may befprovided with a scale 2| which isgraduated to read wind velocity andregisters withan index point 22formed on the outer flange II `of the casing. The scale 2| is graduatedin both directions from a zero point so as to indicate the I velocity ofeither a head wind or tail wind, as

will be described. It is to be understood that the scale 2| can beformed on the stationary iiange II instead of on the ring I5, ifdesired, index 22l then being formed on the ring I5.

For actuating the ring I 5, there is provided va gear 22a carried upon ashaft 23 which is provided with an operating handle, such as a knurledknob 2l, in a readily accessible'position at the front of the casing.lThe gear 22a meshes with a rack 2l formed on the outer periphery ofthering II and extending a suiiicient `distance around the ring to providefor the desired movement thereof. The flange II is provided,

with an arcuate recess 28 which provides clearance for the rack 2B andforms a stop to engage the rack when the ring I5 reaches its extremepositions so as to limit the movement thereof.

For actuating the pointer 30, there is provided suitable mechanismresponsive to speed of movement through the surrounding medium. In theembodiment shown, this mechanism comprises a I propeller 3| which ispositioned inthe surround- -ing medium. as, for example, on the strut ofthe aircraft'. and is connected by suitable remote control mechanism toa standard tachorneterI 32 which' may be either of the mechanical orelectrical typesand includes a mechanism, not

shown, for driving a shaft 33 at a speed proportional to the speed ofrotation of the propeller 3i. This shaft?! drives a standardspeedometerAmechanism 34 (Fig. l) through a` gear train shown as'anidler gear II and a gear. 36

meshing therewith and carried by the shaft. speedometer mechanism -34is` adapted to cause a deectiontof the pointer 30 which is proportionalto the speed of' rotation of the driving mechanism and, consequently',proportional to the speed of movement of the craft through thesurrounding medium.

For integrating the air distance flown, there is provided an odometer l0of standard construction and driven by a gear 4I meshing with a worm 42mounted 'on the shaft 2l, the gear ratio being such that the odometerregisters the distance flown in-suitable units, such as in miles. 'I'heodometer l0 is supported by a suitable means, such as a bracket 43,carried by the casing Il, and Ais visible through an aperature 44 formedin the plate I2.

For indicating the ground miles, or distance travelled with respect toground. there. is provided a second odometer l0 which is supported by ,abracket 5I mounted on the casing Il and is `visible through a suitableaperture, not shown,

in the plate I2. This second odometer Il is driven from the shaft 22 bya gear train including a variable speed device. In the embodiment shown,this gear train comprises a gear I2 mounted upon the shaft Il of theodometer Il,

Y on the periphery` of a'friction disc 51. 'Ihe friction disc 51 drivesa friction wheel 58 driving a second friction disc 5l whichl is mountedupon the-shaft 60 of the odometer In and causes actuation of saidodometer. The disc 51 is mounted on a bracket 6I and may be held infrictional engagement with the wheel 58 by a spring I2 which is adaptedto prevent slippage and to compensate for wear of the parts.

In order to permit control of the` variable speed mechanism tocompensate for the wind velocity, the friction wheel 58n is, mounted forrotation upon a shaft 6I between collars` Si which are pinned to saidshaft. The shaft il is threaded in a rotatable bushing S'Iiournalled ina bracket 68- and is keyed for axial movement in a bracket 69 by meansof a key-way 1l. A-spring 1I, seated aroundthe shaft 6i between thebracket Il and a collar 'I2 formed on said shaft, tends to hold theshaft in a.given set position and to eliminate lost motion.

The bushing 81 is providedwith a bevelled gear 'Ii meshing with a secondbevelled gear 'II carried upon a shaft 'Il which is mounted in a bracket18. 'Ihe shaft I1 carries a worm wheel I9 meshing with a worm gear SIIformed on or secured to the shaft 22, the arrangement being such thatrotation of 'the bushing 81, produced by turning movement of the handle2l, causes the shaft 85 to move axially and thereby shifts the frictionwheel 58 radially oi'. the friction discs l1 and I! so as to change theratio between the speedsof said discs.

jIn the operation of the above-described embodiment, the ring I I isadjusted manually in accordance with the scale 2I and the index mark 22to compensate for; thewind velocity. In the indications are readilyobservable at the same ltime by the pilot., Consequently, he hasaccurate u knowledge of both the air and ground speeds without makingany mental calculations;

At thel same time, the odometer 40, which is driven by the-shaft Il inaccordance with the number of revolutions of the propeller, indi- -catesthe miles iiown with respect to the sur- The setting of the ring Il bymanipulation of the knob 2.4 alsocauses longitudinal movement o! thefriction wheel Il through the mechanism above `described and therebyvaries the speed ratio between the odometer SII and the odometer l0. Theratio of the various gears is such that this change in speed of theodometer 50 compensates for the wind velocity.` Consequently, theodometer 5l is made to indicate the actual ground miles ilown. The pilotthus has available an indication of the actual distance covered as wellas the air and ground speeds and the air miles ilown. This distanceindication is particularly useful, for example, in blind ilying andshows the pilot, without' the necessity of mental calculations, when 'hehas covered the proper distance to reach his destination.

It will be noted that the construction above.

described provides a simple and dependable indicating instrument whichymakes the various readings simultaneously available to the pilot.Furthermore, the adjustment is simple and can be readily effected inflight in accordance with changes in the known wind velocity. The sameadjustment actuates both the ground speed scale and the ground mileodometer and can be made without appreciably diverting the pilotsattentionfrom his other duties.

Although a particular embodiment of the in-V vention has been shown forpurposes of illustration. it is to be expressly understood that theinvention is capable of various uses and that various changes andmodiiications may be made therein as will be apparent to a personskilled in i,

thev art. The instrument has been described, for

' simplicity, as applied to an aircraft. It is evident, however, that itis also applicable to waterborne vessels and the claims are to beinterpreted accordingly. T he invention is only to be limited inaccordance with the following claims when interpreted in view of theprior art.

What is claimed is: f

1 In an indicating instrument, a casing, a stationary disc mountedthereon having a peripheral groove formed therein, a ring having aninner iiange seated in said groove to permit relative rotationalmovement, a rack formed on a. portion of the periphery of said ring, apinion engaging saidv rack to adjust the position of said ring, and anarcuate recess in said casing to provide clearancevfor said rack, theends of saidrecess forming stops to engage said rack for limiting themovement of said ring.

2. In an indicating instrument, a casing, astationary disc mountedthereon, a ring journalled about the periphery of said disc, a rackformed on a portion of the periphery-sof said ring, a

pinion engaging said rack. to adjust the position of said ring, and anarcuate recess in said casing to provide clearance for said rack, theends of said recess forming stops to engage said rack for limiting themovement of said rack. s

3-. In an indicating instrument, a casing having an arcuate recessformed therein, a dial xed tosaid casing, a ring journalled about saiddial, a scale formed on the face o f said ring, a rack formed on aportion of the periphery of'said ring, a pinion engaging saidracktoadjust the position of said ring, said ring having the motion thereoflimited by the ends of the recess in said casing, and a pointer adaptedto' give concurrent indications on said dial and said scale.

' EDGAR L. VAIL.

